High-Throughput Griess Assay of Nitrite and Nitrate in Plasma and Red Blood Cells for Human Physiology Studies under Extreme Conditions

Abstract

The metabolism of nitric oxide plays an increasingly interesting role in the physiological response of the human body to extreme environmental conditions, such as underwater, in an extremely cold climate, and at low oxygen concentrations. Field studies need the development of analytical methods to measure nitrite and nitrate in plasma and red blood cells with high requirements of accuracy, precision, and sensitivity. An optimized spectrophotometric Griess method for nitrite–nitrate affords sensitivity in the low millimolar range and precision within ±2 μM for both nitrite and nitrate, requiring 100 μL of scarcely available plasma sample or less than 50 μL of red blood cells. A scheduled time-efficient procedure affords measurement of as many as 80 blood samples, with combined nitrite and nitrate measurement in plasma and red blood cells. Performance and usefulness were tested in pilot studies that use blood fractions deriving from subjects who dwelt in an Antarctica scientific station and on breath-holding and scuba divers who performed training at sea and in a land-based deep pool facility. The method demonstrated adequate to measure low basal concentrations of nitrite and high production of nitrate as a consequence of water column pressure-triggered vasodilatation in deep-water divers.

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“…For 24hours, the cells were incubated at 37℃. Following incubation, the supernatant was used to estimate nitrite using the Griess nitrite assay 8 .…”

Monolithic Integrated OLED–OPD Unit for Point-of-Need Nitrite Sensing

“…The signal was stable for 1 h after adding the reagents. Brizzolari et al reported a reaction time of 15 min to achieve the most stable results [39]. Pai and Yang evaluated the azo forming kinetics for different concentration of NED and the final acidity [40].…”

A Novel Highly Sensitive Electrochemical Nitrite Sensor Based on a AuNPs/CS/Ti3C2 Nanocomposite

“…The high concentration of nitrite in water mainly comes from industrial wastewater discharge and excessive use of agricultural nitrogen fertilizer, which can directly affect water quality, causing water eutrophication, resulting in bacterial breeding and fish death [ 2 , 3 , 4 ]. Furthermore, a high level of nitrite causes the production of methemoglobin and reduces the oxygen-carrying capacity of red blood cells, which leads to cancer [ 5 ]. The World Health Organization (WHO) states that the concentration of nitrite in drinking water should be below 3 mg/L [ 6 ].…”